Referring to FIG. 1, a lock device 100, such as a conventional one, includes a thumb turn 101 and a latch 102. When the thumb burn 101 is operated, for example, is rotated by a user in a clockwise direction (direction A), the latch 102 is actuated to extend outwardly (direction B) of a door panel 103, and the lock device 100 is in a lock state. Once the door panel 103 is fully closed, the latch 102 extends into a strike plate disposed on a door frame (not shown) so as to hold the door panel 103 in a closed condition. On the other hand, when the thumb turn 101 is rotated in an opposite direction, e.g., the counterclockwise direction, the latch 102 is actuated to retract, and the lock device 100 is in an unlock state, such that the latch 102 disengages the strike plate to allow movement of the door panel 103.